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/* general inverse projection */
#define PJ_LIB__
#include <projects.h>
#include <errno.h>
# define EPS 1.0e-12
/* inverse projection entry */
LP pj_inv(XY xy, PJ *P) {
LP lp;
LP err;
/* cannot const-initialize this due to MSVC's broken (non const) HUGE_VAL */
err.lam = err.phi = HUGE_VAL;
if (0==P->inv)
return err;
/* can't do as much preliminary checking as with forward */
if (xy.x == HUGE_VAL || xy.y == HUGE_VAL) {
pj_ctx_set_errno( P->ctx, -15);
return err;
}
P->ctx->last_errno = errno = pj_errno = 0;
/* de-scale and de-offset */
xy.x = (xy.x * P->to_meter - P->x0);
xy.y = (xy.y * P->to_meter - P->y0);
/* Classic proj.4 functions expect plane coordinates in units of the semimajor axis */
/* Multiplying by ra, rather than dividing by a because the CALCOFI projection */
/* stomps on a and hence depends on this */
if (P->right==PJ_IO_UNITS_CLASSIC) {
xy.x *= P->ra;
xy.y *= P->ra;
}
/* Do inverse transformation */
lp = (*P->inv) (xy, P);
if (P->ctx->last_errno)
return err;
if ((P->left==PJ_IO_UNITS_CLASSIC)||(P->left==PJ_IO_UNITS_RADIANS)) {
/* reduce from del lp.lam */
lp.lam += P->lam0;
/* adjust longitude to central meridian */
if (!P->over)
lp.lam = adjlon(lp.lam);
/* This may be redundant and never used */
if (P->geoc && fabs(fabs(lp.phi)-M_HALFPI) > EPS)
lp.phi = atan(P->one_es * tan(lp.phi));
}
return lp;
}
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